Engine starter



Jan. 30, 1945. ,J. w. FITZ GER/ALB -2,368,292

ENGINE STARTER Filed June .19, 1945 L/b/YH WEZzFpra/d Deceased By j ry F. FilzFpra/d Erecufrix Patented Jan. 30, 1945 UNITED STATES PATENT OFFICE John W. Fitz Gerald-deceased, late of Milwaukee, Wis., by Mary C. Fitz Gerald, executri'x, Milwaukee, Wis., assignor to Briggs & Stratton Corporation, Milwaukee, Wis., a corporation of Delaware Application June 19, 1943, Serial No. 491,513

1 Claim.

nection between the pinion and a pinion actuator so that relative rotation between these parts effects the desired translation of the pinion to and from its operative driving position.

By inertia the pinion stands still (i. e. does not rotate) while the actuator revolves as the starter begins to operate. This provides .the necessary relative rotation between the actuator and the pinion to effect the advance of the pinion toward the ring gear.

At the very inception of this art it was recognized that "resilience must be provided in the chain of torque transmission from the starting motor to the pinion. In the earlier Bendix starters this resiliency was afforded by a helical spring connected between the pinion actuator and a drive head fixed to the motor shaft. This spring had both endwise and torsional resiliency.

Although the Bendix springs were subject to frequent breakage due to crystallization, this early construction was considered standard starter design for many years until the advent of the rubber cushioned starter of the Fitz Gerald Patent No. Re. 20,686, which successively substitutecl a rubber collar for the Bendix spring.

The rubber cushioned starter had many advantages over the old Bendix spring type starter, chief of which was the fact that it obviated the objectionable spring breakage.

The present invention has as its object to provide an engine starter which retains the advantages of a rubber cushioned starter and at the same time dispenses with the need for a rubber or other similar part through the substitution of a novel resilient driving connection between the actuator and the drive head which although of metallic spring construction, is entirely free from the objectionable breakage had in the earlier Bendix spring type starters.

More specifically it is an object of this invention to provide a starter of the type described, wherein the resilient driving connection through which torque is transmitted to the pinion actuator is composed of a stack of cupped spring washers so mounted and assembled that frictional engagernent therebetween provides an impositive torque transmitting connection while at the same gear of an engine to be time the driving connection has the desired endwise resiliency.

With the, above and other objects in view, which will appearas thedescription proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter describedand more particularly defined by the vappended claims, it being understood that such changes in the preciseembodiment .of the hereindisclosed invention -may be made as come within thescope of the claims.

The accompanying drawing illustrates one complete example of the physical embodiment of the invention constructed according to the best mode so far devised for the practical application of the principles thereof, and in which: Figure 1 is a view in side elevation with parts broken away and in section of an engine starter embodying this invention and-showing the pinion in its retracted normal position;

Figure 2 is a view similar to Figure l but illustrating the pinion advanced into-meshw-ith the ring gear;

Figure 3 is a view illustrating part of the starter and showing an alternate manner of retaining -the resilient driving connection properly assembled; and

Figure 4 is a perspective view of a pair of the connected spring washers used in the formation of the resilient drive connection.

Referring now more particularly to the accompanying drawing in which like numerals indicate like parts, the numeral 5 designates the shaft of a starter motor upon which the starter, indicated generally by the numeral 6, is mounted.

As is customary, this starter hasa pinion 1 adapted to be propelled to and from mesh with the ring gear 8 of an engine to be started. The pinion is propelled toward and from the ring gear by relative rotation between it and an ac tuator 9, a threaded connection between these parts effecting the desired translation of the pinion upon relative rotation therebetween.

The actuator 9 is slidably and freely rotatably mounted on a sleeve l0 fitted to the motor shaft and secured thereto by a set screw I l which likewise fixes a drive head l2 to one end of the sleeve and to the motor shaft. At its opposite end, the sleeve l0 hasa pinion stop I3 against which the pinion abuts, as shown in Figure 2,

when fully meshed with the ring gear. Another stop l4 serves to limit endwise movement of the actuator 9 along the sleeve toward the pinion stop, the stop l4 being in the form of a spring ring snapped into an annular groove IS in the sleeve.

Torque is impositively transmitted to the actuator 9 from the drive head through a resilient driving connection I6. This resilient driving connection comprises flanges l1 and It on the drive head and actuator respectively between which a stack of cupped spring washers I9 is assembled. These washers are arranged with their cupped sides alternately facing opposite ends of the stack. In this way, it may be said, the washers are paired as shown in Figure 4 with their outer peripheries engaging and with the pairs of cupped spring washers engaging at their opposite or inner peripheries.

The stack of spring washers thus has endwise resiliency and by virtue of the stop [4 limiting movement of the actuator away from the drive head [2, the stack of washers is held under sufficient compression that the frictional engagement therebetween is adequate to transmit torque to the actuator.

During operation of the starter when the pin ion is fully meshed with the ring gear and bears against the stop I3 the actuator is screwed out rearwardly of the pinion to further compress the stack of spring washers. This increases the frictional engagement therebetween to enable the resilient driving connection to carry the torque necessary to crank the engine. Moreover, it has been found that as the starter continues in service the wear on the contacting peripheral portions of the washers laps them into very intimate contact and thus increases the frictional engagement therebetween.

Cushioning of the application of the cranking load on the starter is obtained both through the movement of the cupped washers, that is endwise flexure of the cupped washers and by slip- If desired, the flanges l1 and I8 of the drive head and actuator may be held against endwise separation beyond a predetermined degree by a shell 20 as shown in Figure 3 in lieu of the stop V M on the sleeve l0.

From the foregoing description taken in connection with the accompanying drawing, it will be readily apparent that this invention provides a starter construction which embodies both endwise and torsional resiliency without the use of rubber or similar material and without incurring the objections of the customary helical spring.

What is claimed as the invention is:

In an engine starter: a tube adapted to be fixed to a power shaft; a drive head on one end of the tube; a screw loose on the tube; a stop on the tube limiting movement of the screw away from the drive head; a plurality of alternately arranged spring washers on the tube confined under pressure between the drive head and the screw with the endmost washers frictionally engaged with the drive head and the screw so that said frictional. engagement plus the frictional engagement adjacent washers provides an impositive torque transmitting connection from the drive head to the screw; a pinion slidable along the tube and having a part threaded on the screw whereby relative rotation between the screw and pinion advances and retracts the pinion; and a pinion stop on the tube to limit advance of the pinion and provide means against which the screw jack action of the threaded connection between the pinion carried part and the actuator reacts to increase the pressure on the stack of spring washers and thereby increase the friction therebetween as the load of the engine is picked up.

MARY C. FITZ GERALD,

page between the Washers; and when the teeth Executrix of the Estate of John W. Fitz Gerald,

abut the cushioning is obtained partly through the resiliency of the cupped washers and partly through slippage.

Deceased. 

